Bacteria have simple structures, lack organelles, and have circular DNA plasmids instead of chromosomes. They have strong cell walls that are resistant to environmental changes. Bacteria can move using flagella, cilia, or be non-motile. Some bacteria move to spread between hosts while non-motile bacteria spread through other means. Gram staining determines the type of carbohydrates in the bacterial cell wall, distinguishing between thick peptidoglycan walls of Gram-positive bacteria and thinner complex walls of Gram-negative bacteria.

1. Bacteria kingdom Characteristics
1. Simplest organisms: Very small size.
2. Lack membrane-bound organelles inside the cell
3. have few internal structures that are distinguishable under a
microscope.
4. genetic information is in a circular loop called a plasmid
(instead of having chromosomal DNA)
5. Strong cell walls: resistant to environmental changes

2. • Transformation
– bacteria incorporate genes from dead bacteria
• Transduction
– viruses insert new genes into bacterial cells.
– This method is used in biotechnology to create
bacteria that produce valuable products such as
insulin

3. Movement
• Flagella ~ Tail like structure the whips
around to propel the bacterium
• Cillia ~ Miniature flagella surround the cell
that help to “swim”
• Non motile ~ Sticky cillia like structures
that keep the bacterium from moving

4. Movement
Some prokaryotes can't
move, while others
have long threadlike
flagella.
If bacteria doesn’t move,
how does it get from
person to person?

5. Flagella

6. Cellular Walls
• Chemical nature of a cell wall can be determined by
Gram Staining
• By finding out what color the cell produces when it is
gram stained you can figure out the type of
carbohydrates in the cell wall

7. Gram + and Gram – Bacterium
Cell Walls

8. Gram-Positive Bacteria
• The cell wall has a thick layer of peptidoglycan 20 to 80
um thick 60-90% of the cell wall is peptidoglycan
• Except for the strptococci most gram positive bacterial
cell walls contain very little protein
Gram-negative Bacteria
• The wall of a Gram-negative bacterium is thinner but
more complex than a Gram-positive bacterium
• Only10 to 20 % of the cell wall is peptidoglycan- the
remainder consists of various polysaccharides,
protein, lipids The cell wall contains an outer
membrane- the LPS